My application completely on maps which show pins and route information and distance between two pins.
For this i am trying to do using OSM maps instead of Google Maps because google maps had certain
limitations if user are increased.So my client wants other maps instead of Google maps.Then after research i came to know OSM is other approach.But it has some limitations for using tile server.But i do not understand what it is.Can any one please tell me what it is and is it better to go with OSM

To have your own Tile Server is not the cheapest solution, but if your application cecomes a success, you might hit the traffic limit that an external Tile Server accepts. It's possible to install a Tile Server on a Linux based OS. So you just have to pay for hardware, bandwidth and power.
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Jens KroghJun 18 '12 at 10:36

A tile server is the service that generates rendered images (tiles) from a database. Hence it requires a lot of storage capacity for both the database and the rendered tiles. Bandwidth and CPU are required, too, but depend mostly on the access frequency of your tile server.

There are also several non-official tile servers with a less restrictive usage policy. However, if they don't fit your needs and you want to know more about setting up your own tile server, visit switch2osm.org.